[lordgrenville]

In Caro's monumental, unfinished biography of LBJ, he basically says that he found no evidence to link him to the assassination, having done decades of incredibly thorough research. But he also describes Johnson as:

- insanely ambitious, and obsessed with becoming President

- devastated at ending up VP, which basically ruled him out from the top job (barring JFK's death)

- insanely secretive (for example, he tracked down and destroyed almost all copies of his college yearbook, which merely showed him as being somewhat disliked/seen as dishonest)

Bearing all of which in mind, I'm partial to this particular conspiracy theory. Though I fully expect that if it's true we'll never know. Johnson was probably unmatched when it comes to pulling off something this audacious and eliminating all evidence.